Principles of Urban Ecology Steward T.A. Pickett Cary Institute of Ecosystem Studies What’s a principle? • Components of Theory •Domain •Assumptions •Concepts •Definitions •Facts •Confirmed generalizations •Laws •Models •Translation modes •Hypotheses •Framework Pickett et al. 2007 Senses of “urban” •Broad – inclusive •Narrow – specific Goal •Framework •Model building Themes •Components •Form •Change •Functioning Components of the system • P1 •Cities are about people and ecosystems. –Human ecosystems The Ecosystem Concept TANSLEY Sir Arthur G. Tansley (1871-1955) The ecosystem concept was created by prominent British plant ecologist, Arthur Tansley, at Oxford University. This diagram now brings all the big ideas in this paper together. Tansley’s core definition of ecosystem was focused on the main topics of his day: organisms and the physical environment. That way of conceiving the ecosystem is outlined in the inner, dashed box. But if we are to take seriously all the kinds of patterns and processes and interactions that the LTER committee identified, then it is useful to include two more kinds of complex within the core idea of the ecosystem appropriate to the 21^st century. People are certainly organisms (or “biota”) but they generate many social structures that are crucial to the structure and functioning of ecosystems. Similarly, they alter the physical complex by moving earth, changing hydrology, building structures for shelter, commerce, and a myriad other purposes, and installing infrastructure to support those buildings and functions. Hence, the contemporary definition of the ecosystem can be expanded – without violating either the letter or the spirit of Tansley’s precedent – to incorporate humans, their institutions and economies, their buildings and engineered networks of transport and communication. Indeed, Tansley, with his awareness of the “exceptionally powerful” human factor, would likely welcome this refinement of his resilient and important concept. P2 •Cities have multiple and changing forms. Central Business District Transitional zone: recent immigrants, deteriorating housing, factories, abandonment Working class zone: single family tenements Residential zone: single family homes with yards and garages Commuter zone: suburbs Burgess Model Application of ecological concepts to understand the spatial distribution or morphology of the urban landscape Burgess put forward a spatially explicit model to describe the structure of the city, and the spatial segregation of groups Based on economic and resource availability, spatial spread outward with “economic mobility” Highly directional, expected to move from one ring to the next Moroc 078 copy Antoni 2001 Jean-Philippe Antoni, « Urban sprawl modelling : A methodological approach », Cybergeo, 12th European Colloquium on Quantitative and Theoretical Geography.St-Valery-en-Caux, France, September 7-11, 2001. St-Valery-en-Caux, France, September 7-11, 2001, article 207, mis en ligne le 01 mars 2002, modifié le 21 février 2007. URL : http://www.cybergeo.eu/index4188.html. Consulté le 02 octobre 2007. SA 2004_JL_3_ 067 Urban areas are very heterogeneous (housing blocks w/ and w/o veg, commercial, in pic) That heterogeneity is at very fine spatial scales There are no tools currently available that allows user to answer these questions P3 •Cities are mosaics extending into surroundings. HERC_outline_GFW Cadenasso Patch dynamics •Applies to cities •Hierarchical •Gradients and fields Pickett, Cadenasso Social processes • P4 •Planned, opportunistic, incremental, incidental. Components of change •Urban design •Urban planning •Topography •Ecology •Social-cultural •Economic P5 •Urban designs as experiments. Felson, Pickett (2005) Jordan Cove, CT Control development Traditional BMP www.bae.ncsu.edu/ P6 •Social, economic, cultural processes influence biophysical processes. res_socveg_notitle 1970 1990 Grove, Burch P7 •Social, cultural, economic complexity. Components of social complexity •Property regimes •Households and individuals •Social status •Economic status •Lifestyle grouping •Social identity •etc. park-interp Perceive high value of parks Perceive low value of parks Troy et al. IKONOS Image Vegetation Parcels PROW Vegetation Private Land Vegetation Fine Scale Analysis Grove, Troy, O’Neil-Dunne Biophysical functions • P8 •Remnant soils, waters, vegetation. Nitrogen retention Suburban Forested Agriculture ----------------- kg N ha-1 y-1 -------------- Inputs Atmosphere 8.7 8.7 8.7 Fertilizer 13.9 0 100 TOTAL 22.6 8.7 108.7 Outputs Streamflow 6.5 0.52 16.4 Retention Mass 16.1 8.2 92.3 Percent 71 94 85 Groffman, Belt, Fisher P9 •Biodiversity multifaceted and present. Mocking bird Mourning dove Catbird Robin Grackle Pigeon Warren, Nilon, Wolf Variation in abundance of A. Northern mocking bird (native); B Mourning dove (native); C. Gray catbird (native); D. American robin (native); E. Common grackle (native); and F. Rock pigeon (exotic) at small neighborhood parks (.25-20acres) in residential areas across the city of Baltimore. Sizes of circles represent the mean number of individuals detected over three point counts in May-June 2002. Methodological principles • P10 •Study-specific definition of urban. mrlc CAP_stats Phoenix, Arizona •Ppt: ~180 mm/yr •Watershed area = 12,000km2 •Study area = 6,400 km2 •Population growth •1950 = 300,000 •2005> 3 million Baltimore, Maryland •Ppt: ~ 1200 mm/yr •Watershed area = 17,000 km2 •Study area = •Population •1950 •2005 2.5 million P11 •Abstract urban gradients. NY CT LI NYBG VCP PBP SWP CEC MRG MLP MSP MSF HSF New York City McDonnell et al 1990 120 km gradient Same soil series Decreasing intensity of surrounding urbanization All oak canopy forests P12 •Human perception as links. Pickett, Cadenasso (2008) Q 1. How is N flux related to landscape structure and the characteristics of households that affect vegetation management? Q 2. What new or underutilized options for structuring and managing vegetation are suggested by the need to reduce N loading? Q 3. How can vegetation management options be expressed as urban designs? Q 4. What physical and social factors affect adoptability of design scenarios? Q 5. Which adoptable design scenarios are preferred, and do preferences vary by neighborhood? Q 6. How do adoptable designs change simulated landscape structure and consequently influence N flux? Practical principles • P13 •Flux of water, and water infrastructure. N. Law and L. Band Changing in landscape structure resulting changes in riparian function and water quality Water principle •Sites of cities •Urban design •Future demands. P14 •Exotic species functions. G. Brush et al. in prep P15 •City form and shared needs –Role of elites –Non-stationary roles –Non-overlapping agency –Environmental injustice. Infant deaths_elevation 1880 Boone P16 •Utility of data requires continual dialog. nowak_map Review of the principles •Human ecosystem •Multiple forms •Extensive spatial mosaics •Intention, opportunity, incidental, constraint •Design as experiment •Role of social pattern and process •Social complexity … • •Retain remnant soils, waters, vegetation •Biodiversity multifaceted, value •Urban definitions various •Abstract gradients of urbanization •Human perceptions and actions •Flux of water, water infrastructure •Exotics and function •City form: equity and control •Application through dialog. • Conclusions •Transdiciplinary concern •Heterogeneous, changing subject •Suggests emerging framework •Open to new insights •Context for specific tests.